#!/usr/bin/env node
const http = require('http'),
      qs = require('querystring'),
      fs = require('fs'),
      log = console.log;

let items = loadItems(),
    result = {
      status: 200,
      reason: 'ok',                      
    };

process.on('SIGINT', () => {
  saveItems();
});

function loadItems(){
  log('loadItems');
  try {
    let items = fs.readFileSync('./12-items.txt').toString('utf8');
    items = JSON.parse(items);
    return items;
  } catch(e){ 
    return []; 
  }
}

function saveItems(){
  log('saveItems');
  fs.writeFileSync('./12-items.txt', JSON.stringify(items));
}
http.createServer((req,res) => {
  //console.log('HTTP request method:', req.method);
  logRequest(req);
  if(req.url.slice(0,5)!== '/todo'){
    let html =fs.readFileSync('./12-todo.html').toString('utf8');
    if(req.url =='/'){
      res.end(html);
    }else if(req.url =='/12-todo.js'){
      fs.createReadStream('./12-todo.js').pipe(res);
    }else{
      res.end('not api request and not page request!');
    }
    return; 
  } 
  switch(req.method){
    case 'GET':
      select(req,res);
      break;

    case 'POST':
      insert(req,res);
      break;

    case 'PUT':
      update(req,res);
      break;

    case 'DELETE':
      remove(req,res);
      break;

    default:
      res.end(`${req.method} method`);
    
  }
  //res.end('Hello world!');

}).listen(8080);

function logRequest(req){
  log(`${req.method} ${req.url} HTTP/${req.httpVersion}`);
  log(req.headers);
  log();
}
function select(req,res){
  result.data = items;
  res.end(JSON.stringify(result));
}
function insert(req,res){
  let data='';
  req.on('data',chunk => data += chunk);
  req.on('end',()=>{
    let item = qs.parse(data).item;
    if(item !== '' && typeof item !== undefined){
      items.push(item);
      res.end(JSON.stringify(result));
    }else{
      result.status = 401;
      result.reason = 'item is empty';
      res.end(JSON.stringify(result));  
    }
  });
}
function update(req,res){
  //get id
  let id = req.url.split(':')[1];

  //validate id
  //data type
  //value min=0,max=items.length
  
  //get item
  let data='';
  req.on('data',chunk=>data +=chunk);
  req.on('end',()=>{
    //update items[id] = item
    let item = qs.parse(data).item;
    if(item!= '' && typeof item != 'undefined'){
      items[id] = item;
      res.end(JSON.stringify(result));
    }else{
      result.status = 402;
      result.reason = 'item is empty';
      res.end(JSON.stringify(result));
    }
  });
}
function remove(req,res){

  //get id
  let id = req.url.split(':')[1];
  //id not exist  del all
  if(typeof id === 'undefined'){
    items=[];
    result.status = 200;
    result.reason = 'delete all sucess';
    res.end(JSON.stringify(result));
    return;
  }
  //id exist
  //valide id
  //id is ok del items[id]
  items = items.splice(id,1);
  result.status =200;
  result.reason = 'del sucess';
  res.end(JSON.stringify(result));
}
